This invention relates to time and attendance recorders and, in particular, to card feed and read mechanisms for such recorders.
The most common use of time and attendance recorders is to document the times and dates when employees are at work. Mechanical systems for marking paper time cards with a stamp indicating the time of day so as to document the hours of work of an employee have been in existence since the early 1900""s. Over the years, such systems have become more sophisticated so that a variety of information can now be printed on a paper time card, including full date information which can be used in determining hours worked and the appropriate rate of pay for those hours.
A particularly xe2x80x9cuser friendlyxe2x80x9d system of this general type is the PTR-4000 Time Recorder sold by Pyramid Technologies of Meriden, Conn. This time and attendance recorder uses numbered paper time cards which are assigned to individual employees as needed. The cards have optically readable marks to encode the number of the card. Such a card 10 is shown in FIG. 1, where the optically readable marks which encode the number of the card are identified by the reference numeral 12. As shown in FIG. 1, card 10 also includes optically readable marks 11 which serve as a timing code for the reading of marks 12 and the printing of information on card 10.
The PTR-4000 Time Recorder includes an internal memory which stores information regarding the various card numbers. In this way, the total hours worked by an employee on a particular day and/or within a particular pay period can be printed on his or her card each time the card is used without the need to read detailed information from the card. Simply by reading the card number and referencing that number to the internal memory, the PTR-4000 Time Recorder can access all of the information needed to provide a complete printout on the card of the information needed by the employer to prepare its payroll and by the employee to confirm that the time he or she has worked has been properly recorded.
Although the PTR-4000 has worked successfully for several years, it has suffered from some disadvantages. In particular, the reading of optically readable marks 11 and 12 has been subject to error. Errors in reading marks 11, i.e., the marks which serve as a timing code, result in either a card non-read or errors in the location at which information is printed on the card. Errors in reading marks 12, i.e., the marks which indicate the card number, result in the internal memory associating the wrong data with a particular employee which is a critical error from both the employee""s and the employer""s perspective.
In accordance with the invention, it has been determined that the errors in reading marks 11 and 12 arise from two sources: (1) variation in the spacing between the time card and the light source/optical sensor used to read the marks; and (2) variations in the amount of ambient light present at the light sensor.
In view of the foregoing, it is an object of this invention to improve the card feeding and reading systems used in time and attendance recorders. More particularly, it is an object of the invention to improve the reliability of such feeding and reading systems.
To achieve these and other objects, the invention in accordance with certain of its aspects provides apparatus for reading marks (11, 12) on a card (10), said card having a front surface and a back surface, said marks being on the front surface, said apparatus comprising:
(a) a light source (15) for illuminating a portion of the front surface of the card;
(b) a light sensor (15) for detecting light reflected from the front surface of the card;
(c) a base member (17) for supporting the back surface of the card; and
(d) a unitary guide and shield member (13) spaced from the base member (17) and defining a channel (22) for receiving the card, said channel having an entrance end (22a) and an exit end (22b), said unitary guide and shield member comprising:
(i) an entrance guide (19) at the entrance end (22a) of the channel for guiding the card into the channel and shielding the light sensor from ambient light;
(ii) an aperture (20) for receiving both the light source and the light sensor; and
(iii) a guide surface (21) for engaging the front surface of the card to maintain a substantially constant distance between said front surface and both said light source and said light sensor.